An update on this topic:
Now that GCC 8 has arrived in Rawhide, there is no project file support
in Gnatmake anymore. In previos releases Gnatmake has been printing
warnings stating that support for project files would be dropped, and
now it has apparently happened.
Consequently, those Fedora packages that were previously built with
Gnatmake have now been rebuilt with GPRbuild. As GPRbuild is still
excluded from x86-32, this means that all Ada packages except for the
compiler itself are now gone from x86-32.
On the other hand, the compiler bug is supposed to be fixed now. Someone
who cares, and has time and a 32-bit Fedora system, could try to
re-bootstrap GPRbuild on x86-32.